Operable seal connector device

ABSTRACT

A seal connector device (1) for achieving a temporary fluid-tight connection between a rotating shaft (17) rotatably connectable to a structure and said structure, wherein the seal connector device (1) comprises said rotating shaft (17) which defines a rotational axis (S-S); a sealing disc (19) extending radially from said rotating shaft (17); at least one first cylinder-piston assembly (100) comprising a cylinder (9) and a piston (21) slidable into said cylinder (9), said piston (21) having a sealing surface (22) facing the sealing disc (19), and the sealing disc (19) having a sealing counter-surface (34) facing the sealing surface (2), said sealing surface (22) being suitable for abutting against said sealing disc (19); said piston (21) being configured to be selectively operated between: a sealing position in which the sealing surface (22) of the piston (21) is at a minimum distance or in contact with the seal ing counter-surface (34) of the disc (19), in order to achieve a temporary fluid-tight connection between the rotating shaft (17) and the structure, preventing a fluid to flow between the sealing surface (22) of the piston (21) and the sealing counter-surface of the disc (19); and a non-sealing position, in which the sealing surface (22) is moved away from the sealing counter-surface (34) of the disc (19) whereby a fluidic seal is absent between the rotating shaft (17) and the structure.

CROSS-REFERENCE TO RELATED APPLICATION

This application is the 35 U.S.C. § 371 national stage application ofPCT Application No. PCT/EP2014/064101, filed Jul. 2, 2014, which claimspriority to and the benefit of, EP Patent Application No. 13176984.6,filed Jul. 18, 2013, both of which are herein incorporated by referencein their entirety.

DESCRIPTION Field of the Disclosure

The present invention generally relates to the field of the temporaryand operably sealing for fluids between a rotatable shaft and astructure wherein the shaft is rotatably engaged.

Secondly, it relates to the field sealing conveyance of a fluid, forexample, a gas, from a fixed conduit to an apparatus that rotates withrespect to the fixed conduit, or to the transfer of a pneumatic pressurefrom a fixed conduit to an apparatus that rotates with respect to thefixed conduit. More particularly, the device relates to a connector fortransferring a fluid or a pneumatic pressure from a fixed conduit to arotating conduit.

Background

The problem of wearing of a gasket, or a seal, mounted interposedbetween a rotatable shaft, for example the shaft of a propeller, and astructure to which the shaft is rotatably engaged, for example the hullof an amphibious vehicle, or of a boat, or of a sloop, is well known.

The above-mentioned prior art has the drawback that the sealing gasketsare worn due to the sliding friction between the input and outputshafts. This involves the need to have to frequently replace them inorder to avoid or reduce the fluid leakages due to an excessive wear,but this often requires very high costs, due not only to the cost of thesealing gaskets, which may be high as such, but especially due to thelabor costs to disassemble the device in which they are mounted, forexample, a wheels-hub unit of a heavy vehicle, for example, a truck orarticulated truck.

Furthermore, such gaskets tend to stiffen upon time, even if they arenot used, thus worsening the sealing ability.

Another drawback of the prior art is that the gaskets, which are incontinuous sliding contact with the structure and/or with the rotatingshaft with respect to the structure, suffer from the operativetemperature, thus involving a worsening of the sealing abilityperformance. In fact, under reduced operative temperatures in coldenvironments, such gaskets tend to increase the rigidity thereof,accelerating the friction wear process thereof and reducing the seal.

The absence of a wear control of such known gaskets could cause leakagesof a fluid through the interspace between the shaft and the structure towhich the shaft is rotatably connected.

For example the known sealing systems may cause leakages of sea waterfrom the outside of the amphibious vehicle, or the boat, towards theinterior of the hull of the amphibious vehicle or boat.

Furthermore, systems for transferring a pneumatic pressure from a fixedconduit to a rotating conduit are known, wherein a hollow rotatingoutput shaft is rotatably coupled to a hollow fixed input shaft, andwherein one or more annular gaskets are arranged in permanent sealcontact with both the input shaft and the output shaft, in order toprevent or reduce a leakage of transferred fluid or pressure into thegap between the two shafts.

The absence of a wear control of such gaskets could cause leakages ofthe fluid to be transferred from the inlet conduit to the outletconduit.

SUMMARY OF THE INVENTION

Therefore, the technical object of the present invention is to provideseal connector device for achieving a temporary fluid-tight sealingbetween a rotating shaft rotatably connectable to a structure and saidstructure, having features such as to obviate the drawbacks mentionedwith reference to the prior art.

Particularly, the object of the present application is to provide a sealconnector device able to activate a fluid-tight seal between a rotatingshaft and a structure which rotatably engages the rotating shaft, onlytemporarily, for example only when it is required by a temporaryimmersion, and to deactivate the seal when it is not required,protecting from wearing the elements which are in sliding contact whenthe seal is activated. Another object of the present application is toprovide a seal connector device able to avoid the need to frequentlyreplace sealing gaskets between the rotating shaft and the structurewhich rotatably engages the shaft.

Another object of the present application is to provide a connector fortransferring fluids, particularly a gas, or pneumatic pressure, from afixed inlet conduit to a rotating outlet conduit, having features suchas to obviate the drawbacks mentioned with reference to the prior art.

Particularly, an object of the present invention is to provide a fluidtransfer connector avoiding the need to frequently replace sealinggaskets between the inlet conduit and the outlet conduit.

A further object of the invention is to implement a fluid transferconnector suitable to transfer very high pneumatic pressures from theinlet conduit to the outlet conduit during a relative rotationtherebetween.

A possible application is the pressurization and adjustment of thepressure of the vehicle tyres while the vehicle runs and while thewheels rotate.

These and other objects are achieved by a seal connector device forachieving a temporary fluid-tight connection between a rotating shaftrotatably connectable to a structure and said structure, according toclaim 1.

Some advantageous embodiments are the object of the dependent claims.

According to a general embodiment of the invention, a seal connectordevice for achieving a temporary fluid-tight connection between arotating shaft rotatably connectable to a structure and said structure,comprises said the rotating shaft defining a rotational axis; a sealingdisc extending radially from said rotating shaft; at least one firstcylinder-piston assembly comprising a cylinder and a piston slidableinto said cylinder, said piston having a sealing surface facing thesealing disc, and the sealing disc having a sealing counter-surfacefacing the sealing surface, said sealing surface being suitable forabutting against said sealing disc.

The piston is configured to be selectively operated between a sealingposition in which the sealing surface of the piston is at a minimumdistance or in contact with the sealing counter-surface of the disc, inorder to achieve a temporary fluid-tight connection between the rotatingshaft and the structure, preventing a fluid to flow between the sealingsurface of the piston and the sealing counter-surface of the disc; and anon-sealing position, in which the sealing surface is moved away fromthe sealing counter-surface of the disc whereby a fluidic seal is absentbetween the rotating shaft and the structure.

Thanks to the features described above, a seal is implemented onlytemporarily by actuating the piston against the rotating disc, forexample only when it is required by a temporary immersion, while theseal is deactivated when it is not required, allowing to protectgaskets, if present, or the mechanical parts which are temporarily inrotation each other.

According to another aspect of the present application, the above andother objects are achieved by a connector for transferring a fluid or apneumatic pressure from a fixed inlet conduit to a rotating outletconduit.

In particular, a transfer connector for transferring a fluid or forapplying a pneumatic pressure from an inlet conduit to an outlet conduitthat may rotate with respect to the inlet conduit, comprises a rotatingshaft defining the outlet conduit therein.

The rotating shaft comprises a sealing disc radially projecting fromsaid rotating shaft.

According to an embodiment, the sealing disc is integral with the shaft.

According to an embodiment, the sealing disc is fixed to the shaft.

According to an embodiment, the connector comprises means for preventingthe sliding of the disc, or of the disc and the shaft, along therotational axis (S-S).

The connector further comprises an insertion chamber to which the inletconduit is sealingly securable, and wherein such chamber leads towardsthe inlet opening of the outlet conduit.

The connector comprises a first cylinder-piston assembly comprising acylinder and a piston slidable with respect to the cylinder, inparticular into said cylinder, wherein the piston has a sealing surfacefacing the sealing disc, and the cylinder is preferably fluidicallyconnected or connectable to the insertion chamber.

The sealing surface of the piston is configured for abutting againstsaid sealing disc (19) to form a seal when it is pressed against thesealing disc.

The piston is configured to be selectively actuated between a sealingposition in which the sealing surface is at a minimum distance or incontact with the sealing disc, in which a fluidic seal is implementedbetween said insertion chamber and said inlet opening of the rotatingshaft outlet conduit, and a non-sealing position in which the sealingsurface is moved away from the sealing disc, in which a fluidic seal isabsent between said insertion chamber and said inlet opening of therotating shaft of the outlet conduit of the rotating shaft.

In accordance with an embodiment, the cylinder is an annular cylindercomprising an outer cylinder wall, for example, arranged radiallyoutwardly of said sealing disc in order to allow the free rotationthereof, an inner cylinder wall co-axial with the outer cylinder wall,an end wall connecting said outer cylinder wall and said inner cylinderwall, in which said outer cylinder wall, said inner cylinder wall, andsaid end wall define an inner annular cylinder space therebetween, andin which said slidable piston is an annular piston slidably received inthe cylinder space and actuatable by varying the pressure in thepressure chamber.

In accordance with an embodiment, the inner cylinder wall has acylindrical tubular shape, and it is configured to be passed through bysaid rotating shaft.

In accordance with an embodiment, the connector comprises a sealingfluid conduit connectable to a sealing fluid source and opening into asealing chamber defined by the piston sealing surface, by the sealingdisc, and by the cylinder to transfer and pressurize a sealing fluid insaid sealing chamber and to provide a sealing layer or film of sealingfluid in a sealing interspace between the piston sealing surface and anopposite sealing counter-surface of the sealing disc.

In accordance with an embodiment, the piston has a thrust surfaceopposite to said sealing surface, in which said thrust surface at leastpartially defines a pressure chamber having a piston-actuating fluidinlet for influencing said thrust surface to move the piston towards thedisc between said non-sealing position and said sealing position.

In accordance with an embodiment, the sealing fluid conduit is incommunication with the piston-actuating fluid conduit and a partial flowof said piston-actuating fluid forms said sealing film.

The connector may advantageously comprise an outlet chamber external tothe cylinder and opposite the insertion chamber.

The outlet chamber may further comprise an outlet hole configured to bepassed through by the rotating shaft.

When the annular piston is in the non-sealing position, the pistonsealing surface is detached or moved away from the sealing disc mountedon the rotating shaft. In such situation, the fluid, after entering theinsertion chamber through the inlet conduit, is free to leak between therotating shaft and the inlet opening, then to pass through an interspacebetween the rotating shaft and the inner cylindrical wall, then to passthrough the space between the piston sealing surface and the sealingdisc, then to pass between the sealing disc and the outer cylinder wall,and finally to advance by leaking out between the rotating shaft and theoutlet opening.

In other terms, when the sealing surface of the annular piston isdetached or moved away from the sealing disc mounted on the rotatingshaft, no seal is implemented between the inlet conduit and the outletopening. In other terms, in this configuration of seal absence, thefluid entering the insertion chamber prefers to pass through the pathwaydescribed above rather than through the outlet conduit.

Instead, when the annular piston is in the sealing position, in whichthe sealing surface is at a minimum distance or in contact with thesealing disc, the fluid is locked by the seal between the annular pistonand the sealing disc, and therefore the fluid, after being leakedbetween the rotating shaft and the inlet opening downstream of theinsertion chamber, cannot further proceed towards the outlet opening. Onthe contrary, such fluid will be invited to pass through the hollowrotating shaft, and therefore through the outlet conduit.

Valve means arranged along the outlet conduit may establish a pressurethreshold value in the insertion chamber, above which the fluid enteringthe insertion chamber manages to access the outlet conduit. This allowstemporarily interrupting the fluid communication between the insertionchamber and the outlet opening when it is desired to transfer a fluid ora pneumatic pressure from the inlet conduit to the outlet conduit.

The above interruption of the fluid communication would occur along theinterspace between the rotating shaft and the inner cylindrical wall andabout the sealing disc.

In this situation, the pressure or the fluid to be transferred isapplied, through the inlet conduit, to the insertion chamber, andtherefore to an opening of the outlet conduit formed by the hollowrotating shaft, in which such opening puts in fluidic communication theinsertion chamber with the outlet conduit.

The fluid or the pneumatic pressure in the insertion chamber would tendto escape through the interspace between the rotating shaft and thecylinder towards the outlet opening.

However, such leakage is prevented or at least strongly reduced by thesealing engagement between the annular piston and the sealing disc.

The only temporarily sealing engagement and the possibility to controlthe pressure of the sealing engagement between the piston and thesealing disc solves the friction wear problem, and allows applyingextremely high pressures from the inlet conduit towards the outletconduit.

Once the desired amount of fluid has been transferred, or a desiredpressure in the outlet conduit or in an application downstream of theoutlet conduit has been reached, for example, in a tyre, an undesiredfluid reflux may be avoided through valve means, for example through acheck valve, associated to the application downstream or to the outletconduit.

In such a manner, therefore, it is not necessary to permanently maintainthe pressure in the insertion chamber or to permanently maintain thesealing engagement between the piston and the sealing disc.

Advantageously, the connector according to the invention, besidesallowing the transfer of a fluid from a stationary conduit to a conduitthat may rotate with respect to the stationary conduit, similarly allowstransferring a fluid from a rotating conduit to a stationary conduit. Inother terms, it also allows an inverse pathway.

For example, such connector may be also used to deflate a wheel duringthe movement of the vehicle.

Furthermore, such connector, besides allowing to transfer a fluid froman inlet conduit to an outlet conduit to increase the pressure in theoutlet conduit, for example to inflate a wheel, also allows suctioning agas from the outlet conduit towards the inlet conduit, for example, toobtain a vacuum in the outlet conduit.

According to a possible embodiment, the connector according to theinvention may be used to obtain a seal that is temporary and drivenbetween a rotating shaft and a fixed structure supporting the rotatingshaft. For example, the connector according to the invention may be usedto achieve a seal between an axis of a propeller in a watercraft or aship. In such a case, the propeller axis replaces the rotating shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will beapparent from the appended drawings, which illustrate embodiments of theinvention, and, together with the general description of the inventionabove, and the detailed description of the embodiments given below,serve to explain the principles of the present invention.

FIG. 1 is a schematic cross-sectional view of a fluid transfer connectoraccording to an embodiment of the invention, having one sealingcylinder-piston unit.

FIG. 1A is a schematic cross-sectional view of a seal connector devicefor achieving a temporary fluid-tight connection between a rotatingshaft rotatably connectable to a structure and said structure accordingto an embodiment of the invention, having one sealing cylinder-pistonunit.

FIG. 2 is a schematic cross-sectional view of a fluid transfer connectorin accordance with a further embodiment of the invention, having twosealing cylinder-piston units.

FIG. 2A is a schematic cross-sectional view of the seal connector deviceof FIG. 1A, having two sealing cylinder-piston units.

FIG. 3 shows a connector according to the invention, having two pairs ofcylinder-piston units;

FIG. 4 shows a connector having two cylinder-piston units cooperatingwith two distinct sealing discs;

FIG. 5 shows an embodiment of a connector according to the invention,having two cylinder-piston units and two sealing discs;

FIG. 6 illustrates a connector as in FIG. 2, comprising a conduitobliquely passing through the disc to supply a fluid amount within therotating shaft;

FIG. 7 illustrates in a sectional view a further embodiment of aconnector according to the invention, in which the piston-actuatingfluid coincides with the fluid to be transferred between the inletconduit and the outlet conduit;

The FIG. 8 schematically shows a pressurization apparatus of a vehicletyre comprising a connector according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1 to 7, a connector for transferring a fluid ora pneumatic pressure from an inlet conduit 2 to an outlet conduit 3 thatmay rotate with respect to the inlet conduit 2 comprises a rotatingshaft 17 defining the outlet conduit 3 therein that has an inlet opening70 and defines a rotational axis (S-S).

The rotating shaft 17 comprises a sealing disc 19 extending radiallywith respect to the rotating shaft.

The rotating shaft 17 comprises an outlet opening 3′ suitable to put incommunication the outlet conduit 3 with a consumption unit or anapplication downstream with respect to the inlet conduit 2, for examplea wheel the pressure of which is to be controlled, or any consumptionunit that needs such fluid to be transferred.

The connector comprises an insertion chamber 5 leading towards the inletopening 70 of the outlet conduit 3, to which the inlet conduit 2 issealingly connectable.

The connector further comprises a cylinder-piston assembly 100comprising a cylinder 9 and a piston 21 slidable in the cylinder 9, inwhich the piston 21 has a sealing surface 22 facing the sealing disc 19,and in which the cylinder 9 is fluidically connected to the insertionchamber 5, for example through an interspace 15 between the rotatingshaft 17 and an inner cylinder wall 12 (FIGS. 1 to 6).

The piston 21 is configured to be selectively actuated between a sealingposition between the inlet conduit 2 and the outlet conduit 3, and anon-sealing position between the inlet conduit 2 and the outlet conduit3.

In the sealing position, the sealing surface 22 is at a minimum distanceor in contact with the sealing disc 19 implementing a fluidic sealbetween the insertion chamber 5 and the inlet opening 70 of the outletconduit 3 of the rotating shaft 17.

In the sealing position the sealing surface (22) of the piston is at aminimum distance or in contact with the sealing disc (19), preventingthe fluid to pass between the sealing surface (22) of the piston and thesealing disc (19), and forcing the fluid to pass between said insertionchamber (5) and the outlet conduit (3) of the rotating shaft (17)through said inlet opening (70);

In the non-sealing position, the sealing surface 19 is moved away ordetached from the sealing disc 19 by removing a fluidic seal between theinsertion chamber 5 and the inlet opening 70 of the rotating shaft ofthe outlet conduit 3 of the rotating shaft 17.

In the non-sealing position between the shaft and the structure thesealing surface (22) is moved away from the sealing disc (19), allowinga fluid to pass through the connector between the shaft and thestructure.

This allows temporarily interrupting the seal in the fluid communicationpathway between the insertion chamber 5 and the external environmentwhen the transfer of fluid or of pneumatic pressurization is actuatedfrom the inlet conduit 2 to the outlet conduit 3. Precisely, the fluidcommunication pathway could occur along the interspace 15 between therotating shaft 17 and an inner cylinder wall 12, and between the sealingdisc 19 and the cylinder 9 (for example FIGS. 1-6).

Through the inlet conduit 2, the pressure to be transferred or the fluidto be transferred is brought in the insertion chamber 5 and to the inletopening 70 of the conduit 3 extending in the insertion chamber 5. Thefluid or pneumatic pressure in the insertion chamber 5 would tend toescape through the interspace between the rotating shaft 17 and theinner cylinder wall 12 outwardly. However, such dispersion is preventedor at least strongly reduced by the engagement seal between the piston21 and the sealing disc 19.

The fact that the sealing engagement is only temporary, and thepossibility to control the pressure of the sealing engagement betweenthe piston 21 and the sealing disc 19 (that rotates together with therotating shaft 17 with respect to an outer housing of thecylinder-piston unit that remains stationary) solves the friction wearproblem and allows transferring high pressures from the inlet conduit 2to the outlet conduit 3 during the relative rotation therebetween.

Once a desired amount of fluid has been transferred, or the pneumaticdesired pressure is reached in the outlet conduit 3 in an application(for example, a tyre) downstream of the outlet conduit 3, an undesiredreflux of fluid may be avoided through valve means 46, for example by acheck valve, connected with the application downstream or the outletconduit 3. Therefore, it is not necessary to permanently maintain thepressure in the insertion chamber 5 or to permanently maintain thesealing engagement between the piston 21 and the sealing disc 19.

According to an embodiment of a connector according to the invention,the rotating shaft 17 within which the outlet conduit 3 is obtained, hasa first free end inserted in the insertion chamber 5, in which such freeend comprises the inlet opening 70 of the outlet conduit 3.

Such a configuration of the connector according to the invention, shownin FIGS. 1, 2, 6, in which the rotating shaft 17 has a free end arrangedin the insertion chamber 5 and a second free end extending outside theconnector 1, is particularly suitable for transferring a pneumaticpressure or fluid from a stationary part of a machine to a rotating partof the machine, or from the structure of a vehicle to a wheel supportedby a monolateral hub. For example, such a configuration is suitable toinflate or to bring to pressure a vehicle tyre, on an axle shaft, forexample, a steering axle shaft.

The valve means 46 comprise a check valve suitable to open/close theinlet opening 70.

According to a possible embodiment, the check valve 46 is actuatable bya actuation piston 74, inserted in an end of the inlet conduit 2, so asto be urged against the valve 46 by the pressure of the fluid enteringthe inlet conduit 2.

The actuation piston 74 may be electrically controlled, for example, bya solenoid, to control the application of pneumatic pressure or thetransfer of fluid from the inlet conduit 2 to the outlet conduit 3.

In such a manner, the check valve 46 is actuated only upon exceeding apreset fluid pressure, or at a preset fluid flow rate, through the inletconduit.

In other terms, the valve means 46 are configured to open the fluidpassage between the insertion chamber 5 and the outlet conduit 3 onlyunder preset conditions of pressure and flow rate of the entering fluid,particularly when the piston 21 is in the sealing position.

In still other terms, the valve means 46 are configured to open thefluid passage between the insertion chamber 5 and the outlet conduit 3upon exceeding a preset pressure threshold of the fluid in the insertionchamber 5, or upon exceeding a preset value of the difference betweenthe pressure in the insertion chamber 5 and the pressure in the outletconduit 3.

Alternatively, the valve means 46 may comprise an electrovalve, forexample driven by an external control unit, for example, to allow thefluid passage from the insertion chamber 5 to the outlet conduit 3 onlywhen the piston 21 is in the sealing position.

In the connector shown in FIG. 1, the cylinder 9 is an annular cylindercomprising an outer cylinder wall 11 arranged radially outer withrespect to the sealing disc 19 allowing the free rotation thereof withrespect to the cylinder 9, an inner cylinder wall 12 co-axial with theouter cylinder wall 11, an end wall 13 connecting the outer cylinderwall 11 with the inner cylinder wall 12.

The outer cylinder wall 11, the inner cylinder wall 12 and the end wall13 define therebetween an inner annular cylinder space 10.

Particularly, the slidable piston 21 may be an annular piston slidablyreceived into the cylinder space 10 and actuatable by varying thepressure in the pressure chamber 24.

The inner cylinder wall 12 may be in a cylindrical tubular shape andconfigured to be passed through by the rotating shaft 17.

The inner cylinder wall has a length value as measured in a directionparallel to the axis S-S such as to allow the free rotation of thesealing disc 19 and the rotating shaft.

The inner cylinder tubular wall 12 is configured to allow the rotationof the rotating shaft 17 therein. Particularly, such inner cylindertubular wall is configured to leave an interspace 15 or a passagewaybetween it and the rotating shaft 17.

A rolling bearing 75 interposed between the rotating shaft 17 and theinner cylinder tubular wall 12 rotatably supports the rotating shaft 17.Alternatively, the rolling bearing 75 may be interposed between therotating shaft 17 and the end wall 13.

According to an embodiment, the outer cylinder wall 11 may be in acylindrical tubular shape.

The connector may comprise a sealing fluid conduit 29 connectable to asealing fluid source 30, for example a sealing fluid pump, and openinginto a sealing chamber 27 defined by the sealing surface 22 of thepiston 21, by the sealing disc 19 by the cylinder 9 for transferring andpressurizing a sealing fluid in the sealing chamber 27. In such amanner, such sealing fluid generates a sealing layer or film of sealingfluid in a sealing interspace between the sealing surface 22 of thepiston and an opposite sealing counter-surface 34 of the sealing disc19.

In such a manner, an amount of sealing fluid, by passing through thesealing conduit 29, reaches the sealing chamber between the sealingsurface 22 of the piston and the sealing counter-surface 34 of thesealing disc 19. Such sealing fluid is, for example, an oil with such aviscosity as to form a fluid layer between the sealing surface of thepiston, which is stationary, and the sealing counter-surface of the disc19, which, instead, rotates. The presence of such sealing fluid in thesealing chamber prevent the fluid entering through the inlet conduit 2from leaking out of the insertion chamber 5 through the bearing 75, theinterspace 15, the sealing chamber 27, forcing such fluid to passthrough the only opening available, which is the inlet opening 70 of theoutlet conduit.

In other terms, such sealing fluid cooperates with the pressure exertedby the piston 21 against the disc 19, thus forming a seal between thepiston 21 and the disc 19, when the piston 21 is in the sealingposition.

For this reason, and as it will be further described below, to achievean excellent seal, it will not always be necessary to bring the piston21 to directly contact the sealing disc 19, but the piston may remain ata distance from the disc 19 that is equal to the thickness of thesealing layer or film of sealing fluid that is formed between thesealing surface 22 of the piston 21 and the sealing counter-surface 34of the disc.

Advantageously, the sealing layer or film of sealing fluid that isformed between the sealing surface 22 of the piston 21 and the sealingcounter-surface 34 of the disc 19 allows avoiding the direct contactbetween the piston 21, which is generally stationary, and the rotatingdisc 19, avoiding in such a manner the sliding friction weartherebetween.

In order to improve the seal between the sealing surface 22 of thepiston 21 and the sealing counter-surface 34 of the disc 19, the sealingsurface 22 of the piston and/or the sealing counter-surface 34 of thedisc may have annular reliefs 78 about the rotational axis S-S, to makethe contact between such surfaces more uniform.

Particularly, the piston sealing surface 22 and the disc sealingcounter-surface 34 may be shaped in a complementary manner to increasethe contact area therebetween and therefore to improve the seal.

The piston 21 also comprises a thrust surface 23 opposite to the sealingsurface 22, and such thrust surface 23 at least partially defines apressure chamber 24 having a piston-actuating fluid inlet forinfluencing the thrust surface 23 to move the piston 21 against the disc19 between said non-sealing position and said sealing position.

In accordance with an embodiment shown in the figures, the sealing fluidconduit 29 is in communication with the piston-actuating fluid conduit25, and a partial flow of the piston-actuating fluid forms the sealinglayer or film.

In this case, the sealing fluid corresponds to the piston-actuatingfluid.

In accordance with an embodiment, the piston-actuating fluid is selectedfrom a liquid and a gas. For example the piston actuation fluid is aliquid selected from oil, for example, for use as an hydraulicactuation, grease, water. It is preferred that the piston-actuatingfluid is a liquid or a grease, since the higher viscosity thereof allowsobtaining a better seal between the inlet conduit and the outletconduit, above all when the sealing fluid coincides with thepiston-actuating fluid. A fluid having a high density and/or a highviscosity is particularly suitable for use as a sealing fluid, since,besides allowing a better seal, it also allows not to be mixed with thefluid to be transferred between the inlet conduit and the outletconduit. However, this does not exclude the use of a gas as the sealingfluid.

The sealing fluid conduit 29 may extend in a branched manner within atleast one between the piston 21 and the disc 19 leading to differentpoints of the sealing chamber 27. In such a manner, the sealing fluidmay be suitably distributed and form a homogeneous sealing fluid layer.

In accordance with an embodiment, at least one between the piston andthe sealing disc 19 forms, for example internally to the piston and/orto the disc, a sealing fluid conduit 33 having an inlet arrangedradially external to the sealing surface 22 or to the sealingcounter-surface 34 and opening in the sealing chamber 27 to form saidsealing film.

The piston 21 is shaped so that an effective thrust area of the thrustsurface 23 of the piston is larger than an effective thrust area of thesealing surface 22 of the piston to allow the piston 21 to be displacedagainst the pressure of the sealing fluid in the sealing position. Insuch a manner, it is avoided that the pressure of the sealing liquid inthe sealing chamber 27 cancels, or overcomes, the force to displace thepiston 21 to its sealing position.

The fact that the pressure of the sealing fluid and/or the pressure ofthe piston actuation fluid is higher than the pressure of the fluid tobe transferred between the inlet conduit and the outlet conduit, ensuresachieving a seal that prevents, in the seal, leakages of the fluid to betransferred between the inlet conduit and the outlet conduit, also whensuch fluid to be transferred is a gas.

The connector, as shown in the FIGS. 1, 2, and 6, may comprise adeflecting plate 79 mounted at the free end of the rotating shaft 17arranged in the insertion chamber 5, about the inlet opening 70 of therotating shaft. This deflecting plate 79 has as its aim to deflect apossible reflux of piston-actuating fluid from the thrust chamber 24 tothe insertion chamber 5, so as to prevent a mixing of suchpiston-actuating fluid with the fluid entering through the inlet conduit2.

In the case that the piston-actuating fluid is a liquid, for example,oil, such fluid, after being refluxed in the insertion chamber 5 andafter being deflected by the deflecting plate 79 precipitates downwardlyin the insertion chamber 5 and it is received by a collection portion 80of the insertion chamber 5.

The insertion chamber 5 may be provided with a discharge opening 35 witha corresponding discharge valve 36 to discharge the residual fluidformed by the piston-actuating fluid leaked in the insertion chamber 5or by a part of the liquid to be transferred from the inlet conduit 2 tothe outlet conduit 3 that has leaked in the insertion chamber 5 throughthe interspace 15, or liquid by a part of fluid/liquid to be transferredfrom the inlet conduit 2 to the outlet conduit 3, fallen in theinsertion chamber at the inlet opening 70 of the outlet conduit 3, orleft in the insertion chamber 5 after the completion of the fluidtransfer.

The discharge valve 36 may be automatically actuated by valve controlmeans, for example, by an actuator actuated by a level of the liquid 37,for example, by a floating switch.

A discharge electric pump 38 (shown in FIG. 6, for example) may beprovided for the removal of such residual fluid in a fluid tank 39. Suchtank may be connected to a recirculation circuit that brings suchentering residual fluid back to the piston actuation fluid conduit 25,or to the sealing fluid conduit 29, for example, by means of the sealingfluid pump 30.

According to an embodiment, for example shown in FIG. 6, the connectormay comprise a return conduit 89 configured to allow the return of thefluid from the outlet conduit 3 to the fluid tank 39, so as to form aclosed fluid circuit. Such an application turns out to be very useful,for example, in the case that a fluid circuit within the wheel isimplemented, for example to heat or cool the wheel during the vehiclemotion.

In accordance with an embodiment, the return conduit 89 comprises anoutlet 89″ leading to the outlet chamber 7 so as to direct said fluid insaid outlet chamber 7 to be able to be then received and conveyed by thepump 38 to the tank 39.

In accordance with an embodiment, the piston 21 may be provided withinner and outer annular gaskets 26 arranged in the interspace betweenthe piston 21 and the inner cylinder wall 12 and the outer cylinder wall11 to hermetically isolate the pressure chamber 24 from the sealingchamber 27, particularly defined by the sealing surface 22 of the piston21, the rotating shaft 17, the sealing disc 19, and the cylinder 9.

The piston 21 may be locked so as not to rotate with respect to thecylinder 9 or, alternatively, the piston 21 may be allowed to rotatewith respect to the cylinder 9. In both cases, the annular gaskets 26are not subjected to friction and wear permanently, but only when thepiston 21 temporarily moves with respect to the cylinder 9.

In accordance with a further embodiment, the piston 21 may be providedwith at least one front annular gasket 28 (shown in FIG. 6) housed inthe sealing surface 22 and extending about the rotating shaft 17,suitable to sealingly engage the sealing disc 19 when the piston 21 isin the sealing position. Also, this at least one front gasket 28 is notsubjected to a permanent friction wear, but only during the sealing.

In the embodiment in which the piston 21 is free to rotate together withthe sealing disc 19 within the cylinder 9, the at least one front gasket28 is almost statically stressed.

In the embodiment in which the piston 21 is prevented from rotatingtogether with the sealing disc 19 within the cylinder 9, the at leastone front gasket 28 is subjected to friction wear only when the piston21 is in the sealing position.

In such a case, the connector comprises at least one slidable engagingmember 42, 43 that allows the piston 21 to slide with respect to thecylinder 9 along the rotational axis S-S, but prevents the piston 21from rotating with respect to the cylinder 9 about the rotational axisS-S.

For example, the slidable engagement is a projecting member 43 integralto the cylinder 9 and slidably engaged to a corresponding slot in thepiston 21 in a direction parallel to the rotational axis S-S (shown, forexample, in the FIGS. 1, 2, 3,4, 5, 7).

According to an embodiment, at least one front gasket may be provided onthe disc sealing surface 34 (not shown). Particularly, such at least onefront gasket in the disc sealing surface may be present in addition orin replacement to the front gasket 28 in the piston 21.

Particularly, the front gaskets 28 may be not necessary in the case thatthe sealing film is sufficient to form a seal under operativeconditions.

In such a case, the important advantage is obtained, of not having toreplace such gaskets, thus decreasing the connector maintenance costs.

In accordance with an embodiment shown in FIG. 1,2, the connector 1 maycomprise an electric connector 81 comprising a stationary portion 82with respect to the inlet conduit 2, and a rotating portion 83 integralto the rotating shaft 17, in which the stationary portion 82 is inelectric communication with the rotating portion 83. Different lengthsof electric or electronic circuits may be connected to the stationaryportion 82 and the rotating portion 83. For example, such electricconnector may connect an electric power source and/or an electricalcentral unit integral to the inlet conduit 2 and sensors or consumptionunits integral to the outlet conduit 3, for example, mounted in a wheelof a vehicle which is fixed to the rotating shaft 17.

The rotating portion 83 may be connected to a consumption unit of thewheel, for example, via the cable 84.

The stationary portion 82 and the rotating portion 83 may beelectrically connected together through sliding contacts or throughelectromagnetic or induction magnetic contacts.

In accordance with an embodiment, shown in FIG. 2, two cylinder-pistonassemblies 100 are arranged on two opposite sides of the sealing disc 19and adapted to be displaced in sealing engagement with the sealing disc19 on both sides of the sealing disc 19, thus creating two sealingbarriers to interrupt the fluid communication between the inlet conduit2 and the outlet conduit 3.

Each cylinder-piston assembly 100 of this embodiment may have the samecharacteristics of the above-described cylinder-piston assembly.

In the connector of this second embodiment, two annular pistons 21 areslidably housed in the cylinder 9 on two opposite sides of the sealingdisc 19 and each piston 21 defines a pressure chamber 24 together withthe cylinder 9.

The piston-actuating fluid conduit 25, or two independent conduits ofpiston-actuating fluid lead to the thrust chambers 24 to pressurize suchthrust chambers 24 to displace the pistons 21 on both sides in sealingengagement with the sealing disc 19, thus creating two sealing barriersfor selectively interrupting or opening the fluid communication betweenthe insertion chamber 5 and the outlet conduit 3.

The connector 1, as shown in FIG. 2, may comprise an outlet chamber 7,arranged on the opposite side of the cylinder-piston assembly 100 withrespect to the insertion chamber 5. Particularly, such outlet chamber 7is passed through in inlet and outlet from the rotating shaft 17, and itis suitable to collect residual fluid that possibly leaks through anoutlet passage 14 of the cylinder-piston assembly 100 arranged on a sideopposite to the cylinder-piston assembly arranged in the proximity ofthe first free end 84 of the rotating shaft 17.

In accordance with a further embodiment (FIGS. 2, 6), the rotating shaft17 defines an inner auxiliary conduit 48 that is separated from theoutlet conduit 3 and that has an opening leading into the sealingchamber 27 of the cylinder 9 for conveying the sealing fluid from thesealing chamber 27 to an outlet port 88 of the sealing fluid outside therotating shaft 17 (for example, for supplying lubricating oil or sealingfluid in a tyre intended to be pressurized) or for dispensing orsupplying the sealing liquid in the sealing chamber 27 of a plurality ofcylinders 9 through the same rotating shaft 17.

According to an embodiment, for example shown in FIG. 3, two pairs ofcylinder-piston assemblies 100 as described above are mounted along asame rotating shaft 17, within which the outlet conduit 3 is defined.

Such embodiment is particularly advantageous in the case that therotating shaft 17 is the axle of a vehicle, joining two opposite wheelsof the vehicle, particularly in the case of an axle for driving wheels.

This embodiment differs from the embodiments of the preceding figures inthat the insertion chamber 5 is interposed between two pairs ofcylinder-piston assemblies 100. As for the embodiments described in thepreceding figures, the insertion chamber 5 is sealingly securable to theinlet conduit 2 and leads to the inlet opening 70 of the outlet conduit3. Therefore, both the inlet conduit 2 and the inlet opening 70 of theoutlet conduit are interposed between the two pairs of cylinder-pistonassemblies 100.

Also elastic suspension means 120 are shown in FIG. 3, which aresuitable to elastically connect the connector 1 according to theinvention, or particularly a case 4 containing the connector, to a fixedstructure, for example, a vehicle.

The FIG. 4 shows an embodiment of a connector according to the presentinvention, comprising two single cylinder-piston assemblies mounted on asame rotating shaft 17.

Each cylinder-piston unit is implemented according to thecharacteristics of the connector of FIG. 1.

The insertion chamber 5 is interposed between two cylinder-pistonassemblies 100, particularly specularly mutually arranged. The insertionchamber 5 is sealingly securable to the inlet conduit 2 and leads to theinlet opening 70 of the outlet conduit 3. Therefore, both the inletconduit 2 and the inlet opening 70 of the outlet conduit are interposedbetween the two cylinder-piston assemblies 100 formed each by a singlepiston 21 and a single sealing disc 19.

A possible embodiment of the connector 1 according to the invention isshown, for example, but without limitation, in FIG. 5, in which twocylinder-piston assemblies are mounted on a same rotating shaft 17. Thetwo cylinder-piston assemblies 100 are mounted specularly to oneanother. Particularly, the inlet conduit 2 has two different oppositeoutlets, each of said outlets facing a thrust chamber 24 interposedbetween said each of said outlets and the thrust surface 23 ofrespective one of said pistons 21. Therefore, the insertion conduit 2separates into two opposite branches that extend parallel to therotational axis S-S of the rotating shaft 17, each of them towards arespective piston 21.

The thrust surface 23 of each of the two pistons 21 may be defined by acavity 23′ obtained in the piston. For example, said cavity is in acylindrical or tubular shape. [00146] The inlet conduit 2 leads intosaid cavity 23′ and comprises an end branch 25′, 25″ at least partiallyarranged slidably within the cavity 23′, and extending parallel to therotational axis S-S so as to allow the piston 21 freely sliding alongthe rotational axis S-S.

A gasket 26′, particularly, may be interposed between the end branch25′, 25″ and the cavity 23′.

Advantageously, the cavity 23′ together with the end branch 25′, 25″forms a thrust chamber 24 to push the piston 21 against the sealing disc19.

Alternatively, the cavity 23′, together with the end branch 25′, 25″ andthe gasket 26′, forms a thrust chamber 24 to push the piston 21 againstthe sealing disc 19.

In the example represented in the figure, two distinct cylindricalpistons 21 and two distinct sealing discs 19 are present, in which thepistons 21 are arranged in a central area of the connector, while thediscs 19 are arranged on opposite sides with respect to said centralarea. When the pressure in the pressure chambers 24 exceeds a thresholdvalue, the pistons 21 move axially away from each other outwardly of theconnector and therefore towards the discs 19.

In the example represented in FIG. 5, two opposite sealing barriers areformed between the inlet conduit 2 and the outlet conduit 3.

A support member 13′ may be provided, comprising a tubular portion 13″having opposite ends, so configured as to be slidably couplable with thecavities 23′ of the pistons.

According to an embodiment, the inlet conduit 2 is obtained within saidsupport member 13′. Furthermore, the insertion chamber 5 is interposedbetween the inlet conduit 2 and the outlet conduit 3 through an opening70′ in the inlet conduit 2, which puts in fluidic communication theinlet conduit 2 with the insertion chamber 5.

Valve means 46 are arranged at this opening 70′, and are configured toopen the fluid passage way from the inlet conduit 2 to the outletconduit 3 only after the pistons 21 completed their movement stroketowards the respective sealing discs 19, therefore only when the pistonsreach the sealing position.

The valve means 146 comprise a second check valve, in particular anormally closed check valve. Such valve is kept closed by virtue of theelastic action of a spring 146′. When the pressure of the fluid withinthe inlet conduit 2 exceeds the elastic reaction of the spring 146′ ofthe valve 146, the fluid opens the valve 146 flowing in the outletconduit 3.

By adjusting or selecting the elastic force of the spring 146′ so thatthe valve 146 opens only after the pistons have reached the sealingposition, an automatic system is achieved, which implements the transferof fluid from the inlet conduit 2 to the outlet conduit 3 only when theseal therebetween has been formed.

FIG. 6 shows an example of the connector 1 having two cylinder-pistonunits 100 suitable to act on opposite sides on a same sealing disc 19.The embodiment of FIG. 6 differs from the one in FIG. 2 for the presenceof a sealing fluid conduit 33 passing through the sealing disc 19extending in a sloped manner with respect to the rotational axis S-Sbetween a radially outer position of the disc and a secondary conduit 48within the rotating shaft 17, to direct a thrust fluid towards aconsumption unit integral to the outlet conduit 3.

According to an embodiment, for example shown in FIG. 6, an impeller 41is formed along an outer periphery of the sealing disc 19 so that, whenthe rotating shaft 17 rotates with respect to the cylinder 9 in apredetermined direction, it pumps the sealing or piston-actuating fluidagainst the leakage thereof through the interspace between the rotatingshaft and the end wall 13.

According to an embodiment shown for example in FIG. 6, the connector 1may comprise an impeller 47 coupled on the rotating shaft 17 suitable togenerate an air flow opposing to the outward fluid leakage from thethrust chamber 24 outwardly through the interspace 14.

According to an embodiment, the sealing disc 19 may have a low-frictioncoating 45 forming the sealing surface of the piston 21 and/or forming acounter-surface of the rotating disc 19. For example, such coating is aPTFE coating applied to said sealing surface 22 or said sealingcounter-surface 34, or in replaceable PTFE plates frontally secured tosaid piston 21 and/or said rotating disc 19.

The connector 1 described above from the viewpoint of the technicalfeatures will be now described from the viewpoint of the operationthereof.

In rest conditions, thus when a sealing connection between the inletconduit 2 and the outlet conduit 3 is not desired, the piston, or thepistons 21, are in the non-sealing position. The rotating shaft 17 isfree to rotate, and no contact is established between the sealing disc19 and the pistons 21.

On the other hand, when it is desired to implement a sealing connectionbetween the inlet conduit 2 and the outlet conduit 3, for example toinflate a vehicle tyre during the vehicle drive, the piston-actuatingfluid is pressurized until moving the pistons 21 forward against thesealing disc 19. At the same time, in those embodiments in which it isprovided, the sealing fluid, which may be or not the samepiston-actuating fluid is pressurized, generating a fluid layer betweenthe sealing surface 22 of the piston 21 and the sealing counter-surfaceof the rotating disc 19. In such a manner, the fluidic seal between theinsertion chamber 5 and the outlet conduit 3 is generated. At thispoint, the passageway between the inlet conduit 2 and the outlet conduit3 is opened, for example by acting on the valve 46.

In such a manner, it is possible to transfer the fluid from the inletconduit 2 to the outlet conduit 3, which is rotating with respect to theinlet conduit 2, while a temporary seal is implemented.

In accordance with an embodiment of the connector 1, for example shownin FIG. 7, the insertion chamber 5 is contained within said innercylinder wall 12, and the piston 21 is hollow and cup-shaped having aninner cavity 71 slidably coupled outside said inner cylinder wall 12, sothat, as the pressure in the insertion chamber 5 increases, the piston21 is urged against the sealing disc 19. In other words, according tothis embodiment, the pressure chamber 24 is defined by the input chamber5.

In accordance with an embodiment, the piston 21 comprises a second checkvalve 146 mounted astride of a head portion 73, suitable to open a fluidpassage through said head portion 73 between the insertion chamber 5 andthe inlet opening 70 in the outlet conduit 3.

In accordance with an embodiment, the second check valve 146 is mountedaligned to said valve 46, and said second valve 146 is actuatable at apressure value in the insertion chamber 5 higher than a pressure valuenecessary to displace the piston, so that said second valve opens apassageway for the fluid only when the piston is in said sealingposition.

In such a manner, as the fluid pressure in the insertion chamber 5increases, the second valve 146 remains closed until reaching a presetpressure value. While the valve 146 is closed, the pressure of the fluidpushing against the thrust surface 23 of the piston moves the piston 21advancing towards the sealing disc 19. When the piston 21 has reachedthe sealing disc 19, the progression of such piston is stopped by thesealing disc 19. As the fluid pressure against the thrust surface 23 ofthe piston 21 further increases, and as the pressure in the insertionchamber 5 contained in the inner cylinder wall 12 increases, suchpressure reaches a pressure value above which the valve 146 opens. Suchvalve 146 is configured so that when the piston 21 is in the sealingposition, when the valve 146 is actuated to open, it actuates to openalso the valve 46. In such a manner, the fluid passage between the inletconduit 2 and the outlet conduit 3 is opened.

The valve 146 is a valve that opens when the pressure to which it issubjected exceeds the elastic force exerted by an expansion spring 146′contained in such valve 146. Thus, the valve 146 opens only uponexceeding a preset value pressure in the insertion chamber.

In this case also, the connector 1 opens the passage between the inletconduit 2 and the outlet conduit 3 only when the piston 21 is in thesealing position.

In this case also, the connector 1 automatically opens the fluid passagebetween the inlet conduit 2 and the outlet conduit 3.

According to an embodiment, a return spring 147 may be arranged betweenthe piston 21 and the cylinder 9, particularly between the piston 21 anda wall 113 rotatably supporting the rotating shaft 17, to displace thepiston 21 from the sealing position to the non-sealing position or restposition.

An example of application of a connector between an inlet conduit and anoutlet conduit that may rotate with respect to the inlet conduit isprovided in FIG. 8.

Particularly, the connector may be used to bring to a desired pressureor to pressurize or inflate a tyre mounted on a vehicle, during thedrive of the vehicle. Therefore, this device allows avoiding stoppingthe vehicle, connecting a pressurized air source to the tyre, andcarrying out the pressurization in such a manner.

A pressurization apparatus 300 for regulating the pressure in a tyreduring the travel of a vehicle supported by such a tyre, may comprise apressurized air source 201, for example, a tank of pressurized airconnected to a pressurized air blower 202. A pressurized air dispenser203 may be provided, interposed between the pressurized air source 201and the inlet conduit 2, for example, to control the pressure in theinlet conduit 2 for example to form the seal and to subsequently openthe passage between the inlet conduit 2 and the outlet conduit 3. In thecase that the connector 1 requires a piston-actuating fluid that isdifferent from the fluid to be transferred between the inlet conduit 2and the outlet conduit 3, for example, such piston-actuating fluid beinga hydraulic oil, a pressure pump 204 is provided to pressurize suchfluid. The pressure pump 204 could be connected to a piston-actuatingfluid tank 205, in which such tank 205 is for example upstream of thepressure pump 204. The pressure pump 204 is connected to thepiston-actuating fluid conduit 25 of the connector 1, so as to act as todisplace the piston 21 and form the seal. Between the pressure pump 204and the connector 1, a dispenser 208 of piston-actuating fluid may beinterposed, to adjust the pressure to actuate the piston or the pistons21. The dispenser 203 and the dispenser 208 may be integrated in asingle dispenser as schematically shown in FIG. 8. A central controlunit 207, for example, a computing unit, may control the dispenser 203and/or 208. The control unit 207, as well as the pumps and the dispensermay, for example, but not necessarily, be supplied by external electricsources via the lines 210.

The dispenser may have, for example, but not necessarily, outlet fluidlines 211, 212 to supply other consumption units.

The connector 1 and the apparatus 300 may be mounted on a pre-existentvehicle, to modify such vehicle. In fact, on large commercial vehiclessuch as, for example, a truck or an articulated truck, both a apparatusfor providing pressurized air and a apparatus for providing pressurizedoil to actuate hydraulic pistons are generally present.

The portion of the apparatus comprising the pressure pump 204 topressurize the piston-actuating fluid may not be present, in the casethat the piston-actuating fluid is the same of with the fluid to betransferred between the inlet conduit and the outlet conduit, as for theembodiments in FIGS. 5, 7, for example.

The present invention may also relate to a vehicle comprising suchconnector 1 and such pressurization apparatus 300.

In accordance with a possible embodiment, the rotating shaft 17 is ashaft of a propeller for propelling, for example an amphibious vehicle,of a ship, of a submarine. In such a case, the seal is implemented onlytemporarily by actuating the piston 21 against the rotating disc, forexample only when it is required by a temporary immersion, while theseal is deactivated when it is not required, allowing to protectgaskets, if present, or the mechanical parts which are temporarily inrotation each other. Such a device may be used also to implement a sealbetween the wheel axles of an amphibious vehicle and its structure, forexample the hull.

In other terms, according to an embodiment, the outlet conduit 3 isreplaced by a shaft or axle of a propeller for propelling a transportmeans, particularly an amphibious vehicle, and the inlet conduit 2 isreplaced by a support structure of said vehicle.

According to an embodiment, the connector (1) is designed to achieve awatertight connection between a rotating shaft, in particular an axle ofa propeller, and a structure of a vehicle, in particular an amphibiousvehicle, wherein the shaft may rotate with respect to the structure, inwhich the connector (1) comprises:

the rotating shaft (17) defining a rotation axis (S-S) and comprising asealing disc (19) extending radially from said rotating shaft (17);

at least one first cylinder-piston assembly (100) comprising a cylinder(9) and a piston (21) slidable into said cylinder (9), said piston (21)having a sealing surface (22) facing the sealing disc (19) and suitablefor abutting against a sealing counter-surface (34) of the sealing disc(19), said piston (21) being configured to be selectively operatedbetween:

a sealing position between the shaft and the structure in which thesealing surface (22) of the piston is pressed against a sealingcounter-surface (34) of the sealing disc, preventing a fluid to passthrough the connector between the shaft and the structure, and anon-sealing position between the shaft and the structure in which thesealing surface (22) is moved away from the sealing disc (19), allowinga fluid to pass through the connector between the shaft and thestructure.

According to an embodiment the connector 1 comprises a sealing fluidconduit 29 connectable to a sealing fluid source 30 and opening into asealing chamber 27 at least partially defined by the sealing surface 22of the piston 21 and by an opposite sealing counter-surface 34 of thesealing disc 19, for transferring and pressurizing a sealing fluid insaid sealing chamber 27 and forming a sealing layer or a film of sealingfluid between said sealing surface 22 of the piston 21 and said sealingcounter-surface 34 of the disc 19, as described above.

Among the various advantages given by the present invention, thefollowing ones may be identified.

The actuation of the connector may be fully automatic and configurableso that the sealing occurs only when preset pressure values in the inletconduit are exceeded, or upon exceeding given pressure difference valuesbetween the inlet conduit and the outlet conduit.

The operation of configuring such connector may take place by selectingthe elastic constants of the springs of the valve means 46 and/or thecheck valve 146.

During running of a vehicle having the connector device, if the tyre ispierced, the continuous insufflation of an air flow rate in the tyrecould match or exceed the air flow rate exiting the hole, avoiding thatthe tyre deflates until reaching a destination.

By controlling the air flow rate input to the tyre when it is driven,the wear of the same tyre may be optimized, besides saving fuel byvirtue of an optimal pressure level within the tyre. In such a manner,the pressure in the tyre may be also adjusted according to the vehicleweight.

A connector according to the invention may be mounted to the vehiclestructure, avoiding having to replace it when the wheel is replaced.

To the above-described preferred embodiments of the device, thoseskilled in the art, with the aim of meeting contingent, specific needs,will be able to make a number of modifications, adaptations, andreplacements of elements with other functionally equivalent ones,without however departing from the scope of the following claims.

The invention claimed is:
 1. A seal connector device for achieving atemporary fluid-tight connection between a structure and a rotatingshaft rotatably connectable to the structure, wherein the seal connectordevice comprises: said rotating shaft, which defines a rotation axis;said structure; a sealing disc extending radially from said rotatingshaft; a first cylinder-piston assembly comprising a cylinder, and apiston slidable with respect to the cylinder in a direction parallel tothe rotation axis, the piston having a sealing surface facing thesealing disc, and the sealing disc having a sealing counter-surfacefacing the sealing surface, the sealing surface being configured to abutagainst the sealing counter-surface of the sealing disc wherein thepiston is configured to be selectively operated between: a sealingposition in which the sealing surface of the piston is at a minimumdistance or in contact with the sealing counter-surface of the sealingdisc to achieve a fluid-tight sealing between the rotating shaft and thestructure temporarily that prevents a fluid to flow between the sealingsurface of the piston and the sealing counter-surface of the sealingdisc; and a non-sealing position in which the sealing surface is movedaway from the sealing counter-surface of the sealing disc such that thefluid-tight sealing between the rotating shaft and the structure isremoved; and a sealing fluid conduit connectable to a sealing fluidsource and opening into a sealing chamber at least partially defined bythe sealing surface of the piston and the sealing counter-surface of thesealing disc, the sealing fluid conduit being configured to transfer andpressurize a sealing fluid in the sealing chamber such that a sealinglayer or a sealing film of sealing fluid between the sealing surface ofthe piston and the sealing counter-surface of the sealing disc isformed.
 2. The seal connector device according to claim 1, wherein thepiston has a thrust surface opposite to the sealing surface, wherein thethrust surface at least partially defines a pressure chamber having apiston-actuating fluid inlet for the sealing fluid to flow through toinfluence the thrust surface to move the piston towards the sealing discbetween the non-sealing position and the sealing position.
 3. The sealconnector device according to claim 2, wherein the sealing fluid conduitis in communication with the piston-actuating fluid inlet, and whereinthe sealing layer or the sealing film is formed by a partial flow of thesealing fluid from the piston-actuating fluid inlet.
 4. The sealconnector device according to claim 2, wherein the piston is shaped sothat an effective thrust area of the thrust surface of the piston islarger than an effective thrust area of the sealing surface of thepiston to allow the piston to be displaced against a pressure of thesealing fluid.
 5. The seal connector device according to claim 1,wherein at least one of the piston and the sealing disc forms orcomprises the sealing fluid conduit having an inlet arranged radiallyexternal to the sealing surface or to the sealing counter-surface, andhaving an opening in the sealing chamber to form said sealing layer orsaid sealing film.
 6. The seal connector device according to claim 1,wherein the cylinder is an annular cylinder comprising an outer cylinderwall configured to allow free rotation of the sealing disc with respectto the outer cylindrical wall, an inner cylinder wall co-axial with theouter cylinder wall, an end wall connecting said outer cylinder wall andsaid inner cylinder wall, wherein said outer cylinder wall, said innercylinder wall, and said end wall define therebetween an inner annularcylinder space; and wherein the piston is an annular piston slidablyreceived into the inner annular cylinder space in a direction parallelto the rotation axis and actuatable by varying pressure in a pressurechamber.
 7. The seal connector device according to claim 6, wherein theinner cylinder wall has a cylindrical tubular shape and is configured toaccommodate the rotating shaft.
 8. The seal connector device accordingto claim 1, further comprising a second cylinder-piston assemblycomprising a cylinder and a piston slidable with respect to the cylinderof the second cylinder-piston assembly in a direction parallel to therotation axis, the piston of the second cylinder-piston assembly havinga sealing surface facing the sealing disc, wherein the piston of thefirst cylinder-piston assembly and the piston of the secondcylinder-piston assembly are arranged to face respectively two oppositesides of the sealing disc in order to be able to abut against thesealing disc on both sides of the sealing disc, thus creating at leasttwo sealing barriers to interrupt fluid communication between an inletconduit and an outlet conduit.
 9. The seal connector device according toclaim 1, wherein the rotating shaft is a shaft of a propeller forpropelling an amphibious vehicle or a sloop, and the structure is a hullof said amphibious vehicle or sloop.
 10. The seal connector deviceaccording to claim 1, wherein the rotating shaft is an axle supportingat least one wheel for travel of an amphibious vehicle or a sloop, andthe structure is a hull of the amphibious vehicle or the sloop.
 11. Avehicle comprising a seal connector device, the seal connector devicecomprising: a rotating shaft, which defines a rotation axis; astructure; a sealing disc extending radially from said rotating shaft; afirst cylinder-piston assembly comprising a cylinder, and a pistonslidable with respect to the cylinder in a direction parallel to therotation axis, the piston having a sealing surface facing the sealingdisc, and the sealing disc having a sealing counter-surface facing thesealing surface, the sealing surface being configured to abut againstthe sealing counter-surface of the sealing disc wherein the piston isconfigured to be selectively operated between: a sealing position inwhich the sealing surface of the piston is at a minimum distance or incontact with the sealing counter-surface of the sealing disc to achievea fluid-tight sealing between the rotating shaft and the structuretemporarily that prevents a fluid to flow between the sealing surface ofthe piston and the sealing counter-surface of the sealing disc; and anon-sealing position in which the sealing surface is moved away from thesealing counter-surface of the sealing disc such that the fluid-tightsealing between the rotating shaft and the structure is removed; and asealing fluid conduit connectable to a sealing fluid source and openinginto a sealing chamber at least partially defined by the sealing surfaceof the piston and the sealing counter-surface of the sealing disc, thesealing fluid conduit being configured to transfer and pressurize asealing fluid in the sealing chamber such that a sealing layer or asealing film of sealing fluid between the sealing surface of the pistonand the sealing counter-surface of the sealing disc is formed.
 12. Thevehicle according to claim 11, wherein the vehicle is an amphibiousvehicle configured to operate the seal connector device in order toactuate the sealing position of the seal connector device when temporaryimmersion of at least part of the amphibious vehicle occurs, and tooperate the non-sealing position of the seal connector device when theamphibious vehicle is not immersed.